1. Field of the Invention
This invention relates generally to the collection and presentation of optical information and, more particularly, to the acquisition, processing, and visible presentation, by way of passive hard copy, of multi-spectral optic information.
2. Statement of the Problem
Physical objects, ranging from microscopic specimens through to items of astronomy, are identified and described by their optical characteristics. The meaning of an object""s xe2x80x9coptical characteristicsxe2x80x9d includes its visible appearance, as well as its reflection, absorption, and generation of optical energy outside of the visible spectrum. The visible representation of the optical characteristics, meaning those that can be seen by a human being, however, must be in the visible spectrum. Therefore, if an object has characteristics in a non-visible portion of light spectrum the characteristics are mapped or translated to the visible portion.
One example mapping or translation is a chemical photographic film that presents visible changes when it is irradiated by non-visible light. A particular example is infra-red film, or a camera using film that shows exposure to both infrared and visible light, but having a light filter blocking all light other than infrared. Using such an infra-red film, or infrared camera, a picture taken, for example, of a person will look like a greenish monocolor image having light and dark areas corresponding to the person""s infrared radiation pattern. Similarly, a picture of a terrestrial area taken from an airborne platform, or from a satellite, using an infrared film or infrared camera will typically appear as a monocolor image, with light and dark areas showing the infrared radiation. A comparable image is seen using ultraviolet film.
Other scientific areas using images obtained from portions of the optical spectra other than the visible bands include, without limitation, medical imaging and astronomy.
In the current art, images taken at a particular optical spectra are displayed on an individual hard copy, or as an individual image placed on a separate, discrete location of a particular hard copy. For example, an astronomy textbook may have on one of its pages a picture of Jupiter as seem through a telescope at the visible wavelengths of the optical spectrum while, on another page, there may be a picture of Jupiter taken through the same telescope using infrared film. Another example is the field of aerial photography and satellite photography where, if an area of interest has different information observable in different portions of the optical spectrum, the person who wishes to study the information is typically provided with a separate hard copy for each of the different spectral bands in which such information exists.
There are problems, however, associated with having, for one item or object of interest, a separate hard copy picture or image for each of a plurality of ranges of the optical spectrum. These problems may cause particular concern in technical areas such as airborne and satellite imaging, and medical imaging, where the cost of error may be high. Examples of such problems include the overhead, including manpower and time, caused by having to keep inventory over plurality of pictures.
Another example problem caused by requiring a separate picture for each spectral band image of an object or geographical area of interest is that the viewer must change his or her visual focus continually, from looking at a picture at one spectral band to looking at another picture at another spectral band. In addition to being inconvenient this increases the probability of human error because the user must remember how something looked in one range of the optical spectrum when looking at it again in another range.
Still another problem with requiring a separate hard copy picture for each range of the optical spectrum is that the pictures may not be aligned or registered properly with one another. For example, the viewer may have a hard copy of a first picture of a ground area, taken from a panchromatic camera on an airborne surveillance platform, in which an area of interest is situated in, for example, the upper left corner of the copy. A second picture of the same ground area, taken from a near infrared (NIR) camera on the same, or another platform may show the same area in its upper right corner.
It will be understood that for purposes of this description the term xe2x80x9cpicturesxe2x80x9d is defined to include, except where another meaning is stated or is obvious from the context in which the term is used, any visible image regardless of the technology or the method by the which it was originally captured. For example a printed form of an image captured by a digital camera is a xe2x80x9cpicturexe2x80x9d for purposes of this description.
The present invention advances the art and overcomes the problems identified above by placing on a single microlens sheet images of an object or area as it appears, or as it can be represented as appearing, within a plurality of wavelength or frequency bands or the optical spectrum, such that the viewer can move or orient the sheet to see the object""s or area""s radiation pattern in any of such bands.
In one embodiment of the invention a detection image is generated by each of a plurality of optical image sensors, each sensor having a particular detection frequency band. A first spectral band digital pixel array, representing the generated detection image from a first band of the optical spectrum is input to a data processor. Likewise, a second spectral band digital pixel array, representing the generated detection image from a second band of the optical spectrum is input to the data processor. The data processor receives, or retrieves a prestored value of, a microlens parameter data specifying physical parameters of a microlens sheet. The data processor generates an output interphased or interlaced digital pixel array based on the first spectral band digital pixel array, the second spectral band digital pixel array, and the microlens parameter data. The output interphased digital pixel array includes information for printing an image representing a rasterized form of the first spectral band digital pixel array interlaced with a rasterized form of the second spectral band digital pixel array. The rasterization is such that a predetermined number of raster lines of each of the first spectral band digital pixel array, in an alternating pattern with a predetermined number of raster lines of the second spectral band digital pixel array, can be overlaid by each microlens of a microlens sheet in accordance with the microlens parameter data. A visible interphased image is printed on a printable surface of a hard copy sheet, the printed image being based on the output interphased digital pixel array, and a microlens sheet is overlaid onto the printable surface.
The output interphased digital pixel array is generated, and the visible interphased image is printed such that when the microlens sheet is overlaid the user sees, from a first viewing position, a first spectral mage of the object or area of interest, which is how it would appear if it were seen in the first spectral band and, from a second viewing position, sees a second spectral image of the object or area of interest, which is how it would appear if it were seen in the second spectral band.
In a further aspect of the invention, the data processor also receives, or retrieves a prestored value of, a printing device parameter data specifying physical characteristics of a printer for applying a visible image to a tangible medium. The output interphased digital pixel array is generated further based on the printing device parameter data.
In one variation of the first embodiment, the microlens sheet comprises a plurality of semi-cylindrical or similar cross-section transparent lenses, lying in a plane and extending parallel to one another. A rotation axis lies in the plane and extends in a direction parallel to the lenses. The first orientation and position includes a first rotation of the hard copy sheet about the rotation axis and the second orientation and position includes a second rotation of the hard copy sheet about the rotation axis.
In a further variation of the first embodiment the microlens sheet comprises a plurality of lenses, each having a circular or elliptical circumference, and each having a hemispherical or aspherical cross-section. A first rotation axis lies in the plane, and a second rotation axis lies in the plane and extends normal to the first rotation axis. The first orientation and position includes a first rotation of the hard copy sheet about the first rotation axis and the second orientation and position includes a second rotation of the hard copy sheet about the first rotation axis.
An objective of the present invention is to display multiple images, each representing the appearance or radiation characteristics of an object or observational area in particular band of the optical spectrum, on a single hard copy. The single hard copy can then be used, for example, in military or law enforcement briefings and then distributed to those involved, e.g., analysts, pilots, special operations persons. The single hard copy can be used in textbooks, periodicals and other publications in the fields, for example, of astronomy and medicine.
These and other objects, features and advantages of the present invention will become more apparent to, and better understood by, those skilled in the relevant art from the following more detailed description of the preferred embodiments of the invention taken with reference to the accompanying drawings, in which like features are identified by like reference numerals.